PERV-ASIVE PROBLEM: Joshua Flecha (in police custody last night), is charged in one of the sex attacks that have plagued Brooklyn.William Miller

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A Heartland Brewery bartender was nailed for one of the Park Slope gropings — and he’s being eyed for several other attacks that have terrorized the area, police sources said yesterday.

Ex-con Joshua Flecha, 32, of Astoria, Queens — who allegedly had his fly wide open and porn on his cellphone when he was arrested Monday — is charged with forcible touching and sexual abuse for allegedly attacking a woman on an F-train platform in May.

He’s suspected in the five other subway-station gropings and some of the street attacks that have plagued Park Slope, Windsor Terrace and Sunset Park since March. Cops put Flecha in a series of lineups Tuesday, but none of the victims of five similar subway attacks could ID him as their attacker, sources said.

There have been 20 incidents, including one rape. A man was arrested for one street attack last week and at least two other creeps remain at large.

When Flecha was busted Monday, he was carrying a bottle of Jack Daniel’s and some pot — and had an X-rated video playing on his cellphone, law-enforcement sources said.

Cops from the 76th Precinct spotted the accused creep acting suspiciously at about 2:30 a.m. on Greenwood Avenue between East Fourth and Fifth streets in Greenwood Heights, and then saw him again 45 minutes later on 17th Street in Park Slope checking out parked cars.

They stopped him and asked what he was doing.

“I don’t know,” he replied, a law-enforcement source said.

Cops saw he was a dead ringer for the suspect in the May 7 attack.

The 37-year-old victim later picked him out of a lineup. She told cops the creep groped her breasts and molested her while exposing himself and masturbating as she tried to swipe her MetroCard.

Cops yesterday were rounding up victims of other attacks to see if they could ID Flecha, who served six months in jail and five years’ probation for a felony DWI conviction on Long Island in December 2009.

Flecha’s ex-mother-in-law told The Post his porn addiction was the main reason her daughter, Michaela — a devout Jehovah’s Witness — divorced him a decade ago.

“He was a porn addict, and he had that problem with the ‘open zipper,’ [if] you know what I mean,” said Deborah Craig, 55, of Snow Hill, Md.

“He was heavily into it.”

A former roommate said yesterday that Flecha was raised on Long Island in a devout family of Jehovah’s Witnesses , but strayed from the faith and became estranged from his parents.

“He was very short tempered, like a drunk,” said Raffi Bagrevandian, 28, who has known the suspect for eight years and roomed with him in Astoria until two weeks ago when their lease was up.

At the Rockefeller Center Heartland Brewery, a co-worker said:

“He’s a very giving person. I’ve never seen him act out in a way that would be harmful to anyone. I think it must be a case of mistaken identity.”